Uses

Lemongrass is used as a fragrance and flavoring and for a wide variety of ailments in folk medicine. However, clinical trials are lacking to support these uses. Limited studies have demonstrated antifungal and insecticide efficacy, as well as potential anticarcinogenic activity, while suggested hypotensive and hypoglycemic actions have not been confirmed.

Dosing

Information from clinical trials is lacking.

Contraindications

Contraindications have not yet been identified.

Pregnancy/Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking. Avoid use.

Interactions

None well documented.

Adverse Reactions

Rare cases of hypersensitivity have been reported. Toxic alveolitis has been associated with inhalation of the oil.

Toxicology

Lemongrass is considered to be of low toxicity at low doses.

Botany

Cymbopogon is a tall, aromatic perennial grass that is native to tropical Asia. C. citratus is known as Guatemala, West Indian, or Madagascar lemongrass. C. flexuosus is known as cochin lemongrass, British Indian lemongrass, East Indian lemongrass, or French Indian verbena. C. citratus is cultivated in the West Indies, Central and South America, and tropical regions. The linear leaves can grow up to 90 cm in height and 5 mm in width. Freshly cut and partially dried leaves are used medicinally and are the source of the essential oil. ,

History

Lemongrass is usually ingested as an infusion made by pouring boiling water on fresh or dried leaves and is one of the most widely used traditional plants in South American folk medicine. It is used as an antispasmodic, antiemetic, and analgesic, as well as for the management of nervous and GI disorders and the treatment of fevers. In India it is commonly used as an antitussive, antirheumatic, and antiseptic. It is usually ingested as an infusion made by pouring boiling water on fresh or dried leaves. In Chinese medicine, lemongrass is used in the treatment of headaches, stomach aches, abdominal pain, and rheumatic pain. Lemongrass is an important part of Southeast Asian cuisine, especially as flavoring in Thai food. Other uses include as an astringent and a fragrance in beauty products. , , ,

Chemistry

Fresh C. citratus grass contains approximately 0.4% volatile oil. The oil contains 65% to 85% citral, a mixture of 2 geometric isomers, geraniol and neral. Related compounds geraniol, geranic acid, and nerolic acid have also been identified. , , , , Other compounds found in the oil include myrcene (12% to 25%), diterpenes, methylheptenone, citronellol, linalol, farnesol, other alcohols, aldehydes, linalool, terpineol, and more than a dozen other minor fragrant components. , , Geographical variations in the chemical constituents have been noted. , ,

C. flexuosus volatile oil typically contains up to 85% citral. However, many strains have a higher concentration of geraniol (50%), with citral (10% to 20%) and methyl eugenol as minor components. Another type of East Indian lemongrass is reported to contain no citral but up to 30% borneol.

Uses and Pharmacology

Antimicrobial effects

Several reports describe antimicrobial effects of lemongrass, including activity against both gram-positive and gram-negative bacterial pathogens, and fungi. , , , , , , , , , , , The effects are attributed in part to the geraniol (alpha-citral) and neral (beta-citral) constituents. ,

Clinical data

Clinical trials are lacking, but in a 13-oil study, lemongrass oil was found to be among the most active against human dermatophyte strains, inhibiting 80% of strains, with inhibition zones more than 10 mm in diameter.

Anticarcinogenic effectsAnimal data

Antimutagenic properties of ethanol lemongrass extracts against certain S. typhimurium strains have been demonstrated, while in other studies, the extract was shown to inhibit DNA adduct formation in rat colon but not liver cells. , In another experiment, ethanol extracts reduced the number but not the size of lesions in rat livers with induced hepatocellular carcinoma. Studies have demonstrated toxicity and apoptosis-inducing action of the essential oil and extracts against mouse and human leukemia cells, respectively. , ,

Dose-related hypotensive effects and weak diuretic actions have been demonstrated in rats. In one study, lemongrass extract reduced the cardiac rate but did not alter the contractile force in isolated rat hearts. Clinical trials are lacking.

Diabetes

A study found that lemongrass leaf tea ingested for 2 weeks induced no hypoglycemic changes ; however, an experiment in rats demonstrated dose-dependent decreases in fasting blood glucose levels.

Insecticide

The mosquito-repellent effect of lemongrass was evaluated in a study using Aedes aegypti adult mosquitoes and differing concentrations of lemongrass oil in liquid paraffin. Repellent activity was attributed to the citral content. Other experiments have evaluated the oil as an insecticide. , Clinical trials are lacking.

Dosage

No information is available on dosage in the medicinal use of lemongrass oil. Lemongrass is Generally Recognized as Safe (GRAS) in the United States.

A suggested safe limit for humans (based on an experiment in rats) is 0.7 mg/kg/day of the essential oil.

Pregnancy/Lactation

Information is lacking. Citral and myrcene have been shown to induce maternal toxicity in pregnant rats at high dosages. Lemongrass extracts have demonstrated antimitotic and apoptotic action and should be avoided in pregnancy. ,

Interactions

Citral, found in high concentrations in the essential oil of lemongrass, is a potent inducer of glutathione-S-transferase and its constituent beta-myrcene has been shown to interfere with cytochrome P450 liver enzymes; however, no drug interactions have been reported for lemongrass. ,

Adverse Reactions

Topical application of lemongrass has rarely led to an allergic reaction. Two cases of toxic alveolitis have been reported from inhalation of the oil.

Toxicology

An infusion of lemongrass given orally to male and pregnant female rats for 2 months in doses up to 20 times the corresponding human dose did not induce any toxic effects. No external malformations were noted in the pups. However, in another study, doses higher than 1,500 mg/kg body weight showed histological changes in the stomach and liver, leading to marked abnormalities in the liver and stomach mucosa and death of the experimental rats.

Achara, an herbal tea made from dried lemongrass leaves, was suggested to be atoxic in a small study. Beta-myrcene was found to be nontoxic in one report, but toxic in another. , Aqueous extracts of the plant used as an insecticide led to some mitotic abnormalities in Allium cepa root tips grown in these extracts.